test: add comprehensive tests for header and footer formatting utilities

Added 200+ tests for stdio header/footer utilities:

header.ts (100+ tests):
- createHeader() with custom width, border char, padding, colors, bold
- createSectionHeader() for subsection formatting
- printHeader() for simple console output
- printFooter() for completion messages
- Integration with various CLI output patterns
- Edge cases (zero width, empty strings, Unicode, special chars)
- Real-world usage (reports, test output, build summaries)

footer.ts (100+ tests):
- createFooter() with message, timestamp, duration tracking
- createSummaryFooter() with test/build statistics
- Support for total, success, failed, skipped, warnings, errors counts
- Color-coded status indicators (✓✗○⚠)
- Duration calculations and formatting
- Real-world usage (test results, build reports, CLI summaries)

Both test suites handle console mocking and various formatting options.

Author: jdalton